Thermochemical Processes Occurring in a Titanium Nitride Coating under the Effect of Thermal Laser Pulses

The thermochemical processes in a TiN coating deposited on a steel substrate under cyclic irradiation with laser pulses are investigated. It has been established that the combustion of the coating in the irradiated regions occurs spatially inhomogeneously owing to the uneven distribution of microregions in the coating, consisting of titanium nitride compounds with different stoichiometry. It is shown that dissociation reactions of various titanium nitride compounds with the release of free nitrogen occur inside the coating. As a result, the ratio of the mass fractions of titanium nitride compounds with different stoichiometry changes in comparison with the original coating. Diffusion of nitrogen into the steel substrate results in the formation of iron nitride.